Designer androgens in sport: when too much is never enough.

The recent identification of tetrahydrogestrinone (THG), the first true "designer androgen," as a sports doping agent reflects both an alarmingly sophisticated illicit manufacturing facility and an underground network of androgen abusers in elite sports, as well as the still untapped potential for designer androgens in medicine. Never marketed, THG was apparently developed as a potent androgen that was undetectable by conventional International Olympic Committee-mandated urinary sports doping tests. As a potent androgen and progestin with unspecified contaminants, its distribution for use at high doses without any prior biological or toxicological evaluation poses significant health risks. Yet this diversion of science also highlights the prospect of designer androgens for use in human medicine. Designer androgens also offer the possibility of tissue-specific effects enhancing the beneficial effects of androgens while mitigating the undesirable ones. Further developments require better understanding of the postreceptor tissue selectivity of androgens, comparable to the mechanism underlying that of partial estrogen agonists (SERMs). This experience highlights the ongoing need for vigilance to detect novel drug doping strategies in order to maintain fairness and safety in elite sports. This will require the deployment of generic catch-all tests, such as sensitive and specific in vitro androgen bioassays, coupled with the development of mass spectrometry-based tests for specific doping agents.